I saw these indicators in use (sort of) this morning. Monitor on P3 
showing the 0800 to Edinburgh, but the train was the Royal Scotsman with 
two Class 37s at the head. Both loco's were ahead of the signal, so I 
immediately see how they are used.

Pity my train doesn't normally look like that!

-- 
Doug
"Doug's cool. He's metal ;)" - Fnook
Ignore the old spamtrap work address; mail me on: doug at fruitloaf dot net
http://suicidegirls.com/?hungrydoug